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The focus of Statistical
Experiments (and the companion module Probability, Sampling
and Hypothesis Testing) is on applying statistics to test for
differences between a proposed “model” of a “process”
and the real “process.” The modeling (learning) process
is accomplished through repeated inductive and deductive steps,
the first being inductive model development (i.e. a hypothesis,
a conjecture, or a theory) based on data (facts or observations).
The second step involves model testing where new data is collected,
with either an acceptance of the model or the inductive creation
of a modified or new model followed by new testing.
While the Probability, Sampling and Hypothesis Testing
module focuses on the statistical tools required to make comparisons
between two variables, Statistical Experiments focuses
on expanding the number of variables to more than two.
Plan Do Study Act Cycle
G.E.P. Box ‘s “inductive and deductive” PDSA cycle
is discussed in detail in Chapter One of Statistics for Experimenters
and in an article in Quality Progress where he discusses
the Wright Brothers’ application of this deductive-inductive
process in hundreds of experiments that made it possible for the
first flight. Moen, Nolan and Provost in their book discuss this
deductive-inductive improvement cycle in the more familiar context
of the Shewhart or Deming cycle or as we typically know as the Plan-Do-Study-Act
Cycle (see Chapter One of Improvement of Quality).
In this improvement process, we first focus on our current knowledge
by answering the following questions:
• Who are our customers?
• What are their needs and expectations?
• What do we want to accomplish in order to improve our products
or services for the customer?
• How will we know that a change is an improvement? (This
requires measures! I.e. Garvin’s Eight Dimensions on Quality
– Performance, Features, Reliability, Conformance, Durability,
Serviceability, Aesthetics, and Perceived Quality)
An example can be found by downloading an article on applying
Garvin’s dimensions
to construction management written by Curtin University of Technologies
School of Architecture.
• Finally, what changes can we make that will result in an
improvement? (What is our theory?)
Pre-Activity
You are considering buying a new pen and are evaluating three pens
for possible purchase. Develop a decision matrix based on Garvin’s
eight points. Be prepared to share your outcomes in-group and on
the discussion board.
Possible pens could include a BiC round stic, BiC round stic Grip,
papermate Xtend soft grip, a Pilot G-2 retractable Soft grip, Parker
retractable ballpoint or one of your own choice.
References:
- Box, G. E. P. (1997). Scientific method: The generation of knowledge
and quality. Quality Progress, 30, 47-50.
- Box, G. E. P., Hunter, W. G., & Hunter, J. S. (1978). Statistics
for experimenters. New York: John Wiley & Sons.
- Duncan, A. J. (1986). Quality control and industrial statistics,
5th ed., Irwin, Homewood, IL.
- Garvin, D.A. (1987). Competing on the eight dimensions of quality.
Harvard Business Review, 65(6), 101-9.
- Griffiths, J. R., Evaluation of the JISC information environment:
Student perceptions of services. Information Research, Vol. 8
No. 4, July 2003
Retrieved from http://informationr.net/ir/8-4/paper160.html
- Moen, R. D., Nolan, T. W., & Provost, L. P. (1999). Quality
Improvement through Planned Experimentation (2nd ed.). New York:
McGraw-Hill.
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